Buttigieg has already earned his way on the stage in the first Democratic debate this June. He did it by surpassing the number of donors required. Candidates may earn their way into the debate by showing good support in the polls, or by showing good donor support. The required number of donors is 65,000. After declaring his candidacy, Buttigieg got donations from at least 76,000 people.
Add to this the fact that, after the murder of muslims in New Zealand by a white nationalist, Buttigieg was quick to call out white nationalism as a vile belief (see tweets below). He also issued an official letter as mayor to the muslim community, assuring them that they are a valued part of the community (see letter below).
In spite of my initial reticence, Buttigieg may be for real as a possible nominee.